Fiber-reinforced resin pipe

Abstract

To provide a fiber-reinforced resin pipe capable of achieving thinning of a pipe wall while maintaining impact resistance.SOLUTION: A fiber-reinforced resin pipe comprises a tubular core material layer 2 and at least one of an inner fiber layer 3 formed by impregnating resin into fibers laminated on an inner side of the core material layer 2 or an outer fiber layer 4 formed by impregnating resin into fibers laminated on an outer side of the core material layer 2, wherein at least one of the inner fiber layer 3 or the outer fiber layer 4 includes an axial fiber layer 3b, 4b having rovings 5a arranged at predetermined intervals along a pipe axial direction, an interval between the rovings 5a of the axial fiber layers 3b, 4b being within a range of 0.1 mm to 2.5 mm, and a pipe wall thickness being within a range of 5 mm to 10 mm.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced resin pipe. [Background technology]

[0002] For example, a fiber-reinforced resin pipe as shown in Patent Document 1 below is sometimes used as a cable protection tube to protect cables such as electric cables. As shown in FIG. 1 of this document, this fiber-reinforced resin pipe is formed by laminating fiber layers (fiber-reinforced resin layers 12) in which reinforcing fibers are impregnated with resin inside and outside a core layer (in this document, resin mortar layer 11 made of resin mortar; the same applies below). When forming the fiber layers, multiple layers with different orientations of reinforcing fibers (for example, axial fiber layers and non-axial fiber layers) may be arranged, as shown in Patent Documents 2 and 3 below.

[0003] This fiber layer is made by arranging a predetermined number (from a few to a few tens) of strands (several hundred glass filaments with a fiber diameter of several tens of micrometers) together with a binder to form a roving, and then impregnating this roving with resin. The strength (impact resistance, etc.) of the fiber-reinforced resin pipe is ensured by the action of the laminated core layer and fiber layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3352368 [Patent Document 2] Patent No. 6625729 [Patent Document 3] Patent No. 6716778 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, efforts to reduce the cost of fiber-reinforced plastic pipes have led to the development of thinner pipes. This thinning primarily targets the core layer, which is the thickest of the layers that make up a fiber-reinforced plastic pipe. However, because the core layer, along with the fiber layer, contributes to the impact resistance of the fiber-reinforced plastic pipe, the impact resistance decreases as the core layer is thinned. For example, there is a risk that a tool may pierce the fiber-reinforced plastic pipe during work.

[0006] Therefore, an object of the present invention is to achieve both a reduction in the pipe thickness of a fiber-reinforced resin pipe and its impact resistance. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: The inflatable saddle has a cylindrical core layer and at least one of an inner fiber layer formed by impregnating fibers laminated inside the core layer with a resin and an outer fiber layer formed by impregnating fibers laminated outside the core layer with a resin, A fiber-reinforced resin pipe is configured (first configuration) in which at least one of the inner fiber layer and the outer fiber layer has an axial fiber layer having rovings arranged at predetermined intervals along the pipe axis direction, the roving intervals in the axial fiber layer are within the range of 0.1 mm to 2.5 mm, and the pipe thickness is within the range of 5 mm to 10 mm.

[0008] The axial fiber layer in the first configuration mainly serves to improve the impact resistance of the fiber-reinforced resin pipe (for example, to prevent breakthrough by a tool). By setting the roving spacing of the axial fiber layer within the above range, the impact resistance of the axial fiber layer can be maximized.

[0009] In the first configuration, it is preferable to have the inner fiber layer (second configuration). In this case, an impact acting on the fiber-reinforced resin pipe is first absorbed by the core layer, and any impact that cannot be absorbed by the core layer is then absorbed by the inner fiber layer, thereby reliably preventing the fiber-reinforced resin pipe from being broken through by a tool.

[0010] In the first or second configuration, the basis weight of the axial fiber layer is 250 g / m 2 The above configuration (third configuration) can be adopted, and this can improve the impact resistance provided by the axial fiber layer.

[0011] In the first or second configuration, the spacing between the rovings in the axial fiber layer may be in the range of 0.1 mm to 2.0 mm (fourth configuration). Furthermore, in the fourth configuration, the basis weight of the axial fiber layer may be 325 g / m 2 The above configuration (fifth configuration) can be adopted, which can further increase the impact resistance provided by the axial fiber layer.

[0012] In the first to fifth configurations, the axial fiber layer may be a single layer (sixth configuration), which can minimize the pipe thickness of the fiber-reinforced resin pipe.

[0013] In the first to sixth configurations, the roving may be a glass roving (seventh configuration), which allows the fiber-reinforced resin pipe to be manufactured at low cost. [Effects of the Invention]

[0014] In this invention, the fiber layer has an axial fiber layer having rovings arranged at a predetermined interval along the pipe axis direction, the roving spacing of the axial fiber layer is within the range of 0.1 mm to 2.5 mm, and the pipe thickness is within the range of 5 mm to 10 mm.This configuration allows the impact resistance provided by the axial fiber layer to be maximized, and makes it possible to achieve both a thinner pipe thickness and impact resistance for the fiber-reinforced plastic pipe. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a partially cutaway front view showing one embodiment of a fiber-reinforced resin pipe according to the present invention; [Figure 2]FIG. 2 is a perspective view showing the layer structure of the fiber-reinforced resin pipe shown in FIG. [Figure 3] A front view showing an example of one-way woven glass roving [Figure 4] Front view showing the configuration of the impact test device DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a fiber-reinforced plastic pipe 1 (hereinafter referred to as an FRPM pipe 1) according to the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, the FRPM pipe 1 according to this embodiment is a pipe with a nominal diameter of 125 mm and a pipe wall thickness of 6 mm, which has a cylindrical core layer 2, an inner fiber layer 3 made of resin-impregnated fibers laminated on the inside of the core layer 2, and an outer fiber layer 4 made of resin-impregnated fibers laminated on the outside of the core layer 2.

[0017] The core layer 2 is the layer that forms the core of the FRPM pipe 1, and in this embodiment, resin mortar is used as its material. This resin mortar is made by mixing silica sand as aggregate with unsaturated polyester resin and hardening it. The core layer 2 absorbs external impacts (for example, impacts from tools during work). Note that the material for the core layer 2 is not limited to resin mortar, and it is possible to make an FRP pipe using foam materials such as polyvinyl chloride, polyethylene, styrene, urethane, and polypropylene, as well as recycled materials such as slag discharged from blast furnaces and FRP waste.

[0018] The inner fiber layer 3 is composed of three layers, from the outside in: a circumferential fiber layer 3a, an axial fiber layer 3b, and a circumferential fiber layer 3c. That is, the single-layer axial fiber layer 3b is sandwiched between the circumferential fiber layers 3a and 3c. The outer fiber layer 4 is composed of two layers, from the outside in: a circumferential fiber layer 4a and an axial fiber layer 4b. The axial fiber layers 3b and 4b primarily serve to improve the impact resistance of the FRPM pipe 1 (e.g., to prevent breakthrough by tools), while the circumferential fiber layers 3a, 3c, and 4a primarily serve to maintain the shape of the rovings constituting the axial fiber layers 3b and 4b, preventing the gaps between them from widening, thereby maintaining the impact resistance provided by the axial fiber layers 3b and 4b. The thickness of the inner fiber layer 3 and the outer fiber layer 4 are approximately the same.

[0019] The axial fiber layers 3b, 4b are formed by impregnating a single-sided woven roving 5 with a resin and then curing the resin. As shown in FIG. 3, the single-sided woven roving 5 is a blind-like sheet formed by fastening multiple rovings 5a arranged parallel to each other at a predetermined interval with multiple connecting threads 5b such as polyester threads. In this embodiment, glass roving made of glass fiber is used. This glass roving is formed by bundling several hundred glass filaments with a fiber diameter of several tens of micrometers using a binder to form strands, and then aligning these strands to a predetermined number (several to several tens). In addition to glass fiber, carbon fiber, metal fiber, etc. can also be used as the reinforcing fiber. Furthermore, thermosetting resins such as unsaturated polyester resin, epoxy resin, and phenolic resin can be used as the resin impregnated into the single-sided woven roving 5.

[0020] The axial fiber layers 3b, 4b are formed by arranging the glass rovings of the one-way woven roving 5 so that they are aligned along the axial direction of the FRPM pipe 1. The "axial direction" of the glass rovings that make up the axial fiber layers 3b, 4b does not need to be exactly the same as the axial direction of the FRPM pipe 1, and may be offset from the axial direction of the FRPM pipe 1 by ±10 degrees.

[0021] The size of the spacing (gap) between the glass rovings of the one-way woven roving 5 used in the axial fiber layer 3b of the inner fiber layer 3 is about 2.5 mm, and the basis weight is about 250 g / m 2 On the other hand, the size of the spacing between the glass rovings of the one-way woven roving 5 used in the axial fiber layer 4b of the outer fiber layer 4 is about 5.0 mm, and the basis weight is about 100 g / m 2 That is, the inner fiber layer 3 has narrower intervals between the glass rovings than the outer fiber layer 4, and uses a single-woven roving 5 having a larger basis weight.

[0022] The circumferential fiber layers 3a, 3c, 4a are formed by winding glass roving in the circumferential direction of the FRPM pipe 1. The winding angle of the glass roving in the circumferential direction can be determined appropriately.

[0023] Protective layers (inner protective layer 6, outer protective layer 7) are provided on the inner side of the inner fiber layer 3 and on the outer side of the outer fiber layer 4. Each of the protective layers 6, 7 is made of a resin mixed with non-directional glass fibers, and the resin may be a thermosetting resin such as an unsaturated polyester resin, an epoxy resin, or a phenolic resin, or a thermoplastic resin.

[0024] The FRPM pipe 1 according to the present invention is manufactured by a filament winding method. In this method, the inner protective layer 6, inner fiber layer 3 (circumferential fiber layer 3c, axial fiber layer 3b, circumferential fiber layer 3a), core layer 2, outer fiber layer 4 (axial fiber layer 4b, circumferential fiber layer 4a), and outer protective layer 7 (all uncured) that make up the FRPM pipe 1 are wound in this order around a cylindrical mold, and then heated in an oven. After the layers have hardened by heating, the mold is removed to obtain the FRPM pipe 1.

[0025] The impact resistance of the FRPM pipe 1 according to the present invention was evaluated using an impact testing device 8 shown in Figure 4. This impact testing device 8 has an arm 10 that swings around a swing axis 9. The tip of this arm 10 is equipped with a weight 11 and a protrusion 12 that resembles the tip of a pickaxe used during work. In the test standby state, the tip of the protrusion 12 is located in a horizontal plane that includes the swing axis 9. The FRPM pipe 1 used as the test material is leaned against a support wall 13. When the arm 10 is swung down in the standby state, the tip of the protrusion 12 comes into contact with the surface of the FRPM pipe 1. The weight 11 of this impact testing device 8 weighs 15.75 kg, and in the standby state, the horizontal distance between the FRPM pipe 1 and the tip of the protrusion 12 is 1000 mm.

[0026] In this impact test, existing FRPM pipes A and B and the present invention's FRPM pipes A and B shown in Table 1 were used as test materials.

[0027] Like the FRPM pipe 1 according to the present invention, the existing FRPM pipes A and B each have an inner fiber layer on the inside of the core material layer and an outer fiber layer on the outside. Each fiber layer is made of unidirectional woven roving (basis weight: approximately 100 g / m) with a roving spacing of approximately 5.0 mm. 2 ) and a circumferential fiber layer made of glass roving. The pipe thickness (normal pipe thickness) of the commonly used existing FRPM pipe A is currently 10mm to 13mm, corresponding to the nominal diameter. On the other hand, the pipe thickness (thin-wall pipe thickness) of existing FRPM pipe B, which has been made thinner by reducing only the thickness of the core material layer of existing FRPM pipe A, is 6mm to 7mm, corresponding to the nominal diameter.

[0028] The FRPM pipes A and B of the present application, which are the FRPM pipes 1 according to the present invention, have the same structure as the existing FRPM pipes A and B in the outer fiber layer 4, but differ in the structure of the inner fiber layer 3. That is, the inner fiber layer 3 of the FRPM pipe A of the present application is made of one-way woven roving 5 (basis weight: about 250 g / m) with a roving spacing of about 2.5 mm. 2The inner fiber layer 3 of the FRPM pipe B of the present invention is made up of an axial fiber layer 3b made of a single-woven roving 5 (basis weight: about 325 g / m) with a roving spacing of about 2.0 mm. 2 The FRPM pipes A and B of the present invention are each composed of an axial fiber layer 3b made of a glass roving and circumferential fiber layers 3a and 3c made of a glass roving. The pipe thickness (thin-wall pipe thickness) of both pipes A and B is set to 6 to 7 mm corresponding to the nominal diameter.

[0029] The results of the impact test are shown in the evaluation column in Table 1. The symbols in this column indicate that "x" indicates that the tip of the projection 12 of the impact test device 8 penetrated into the interior of the FRPM pipe 1, "○" indicates that penetration of the tip of the projection 12 of the impact test device 8 into the interior of the FRPM pipe 1 was almost completely prevented, and "◎" indicates that penetration of the tip of the projection 12 of the impact test device 8 into the interior of the FRPM pipe 1 was completely prevented.

[0030] For existing FRPM pipe A, penetration of the tip of the projection 12 of the impact test device 8 into the interior of the pipe was almost completely prevented for all nominal diameters. On the other hand, when the pipe thickness was made thin by simply reducing the thickness of the core material layer 2, as in existing FRPM pipe B, the impact absorption ability of the core material layer 2 was reduced, and therefore penetration of the tip of the projection 12 of the impact test device 8 into the interior of the pipe could not be prevented.

[0031] On the other hand, the present FRPM pipe A was able to almost completely prevent the tips of the projections 12 of the impact test device 8 from penetrating into the pipe interior at all nominal diameters. This is because, by narrowing the roving spacing in the axial fiber layer 3b compared to the existing FRPM pipe 1, the inner fiber layer 3 was able to effectively absorb the impact that could not be fully absorbed by the reduced-thickness core layer 2. Furthermore, by narrowing the roving spacing in the axial fiber layer 3b even more than in the present FRPM pipe A, as in the present FRPM pipe B, the impact absorption effect of the inner fiber layer 3 was further enhanced, and it was possible to reliably prevent the tips of the projections 12 of the impact test device 8 from penetrating into the pipe interior.

[0032] [Table 1]

[0033] In the FRPM pipe 1, at least one of the inner fiber layer 3 and the outer fiber layer 4 has axial fiber layers 3b, 4b with rovings 5a arranged at predetermined intervals along the pipe axis, the spacing between the rovings 5a in the axial fiber layers 3b, 4b being between 0.1 mm and 2.5 mm, and the pipe thickness being between 5 mm and 10 mm, thereby maximizing the strength-enhancing effect of the axial fiber layers 3b, 4b and achieving both a thinner pipe thickness and improved impact resistance for the FRPM pipe 1. In particular, the configuration including the inner fiber layer 3 ensures that an impact acting on the FRPM pipe 1 is first absorbed by the core layer 2, and any impact not fully absorbed by the core layer 2 is then absorbed by the inner fiber layer 3, thereby preventing the FRPM pipe 1 from being pierced by a tool.

[0034] If the pipe thickness is within the range of 5 mm to 10 mm, the layer structure of the FRPM pipe 1 can be changed. For example, a fiber layer made of one-way woven roving 5 having glass rovings inclined at 45 degrees in both the axial and circumferential directions can be newly provided between the axial fiber layer 3b and the circumferential fiber layers 3a, 3c that constitute the inner fiber layer 3. If the pipe thickness exceeds 10 mm, one or both of the protective layers 6, 7 may be omitted.

[0035] In addition, the FRPM pipe 1 has a basis weight of the axial fiber layers 3b and 4b of 250 g / m 2 With the above-mentioned configuration, the impact resistance of the axial fiber layers 3b, 4b can be improved. In particular, when the roving spacing of the axial fiber layers 3b, 4b is within the range of 0.1 mm to 2.0 mm, and the basis weight of the axial fiber layers 3b, 4b is 325 g / m 2The above configuration further enhances the impact resistance of the axial fiber layers 3b, 4b. The roving spacing in the axial fiber layers 3b, 4b is set to a range of 0.1 mm to 4.0 mm. If the roving spacing is greater than 4.0 mm, impact resistance will be insufficient, and if it is less than 0.1 mm, problems such as molding defects and insufficient resin impregnation may occur.

[0036] Furthermore, in the above-described FRPM pipe 1, the axial fiber layers 3b, 4b are configured to be single layers, which minimizes the pipe thickness of the FRPM pipe 1. Furthermore, the rovings 5a that make up each of the fiber layers 3, 4 are configured to be glass rovings, which allows the FRPM pipe 1 to be manufactured at low cost.

[0037] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. Therefore, the scope of the present invention is defined by the claims, not by the above description, and is intended to include the meaning equivalent to the claims and all modifications thereof.

[0038] For example, in the above embodiment, the inner fiber layer 3 and the outer fiber layer 4 are provided on the inside and outside of the core layer 2, but it is also possible to provide only the inner fiber layer 3 on the inside of the core layer 2. It is also possible to provide only the outer fiber layer 4 on the outside of the core layer 2. [Explanation of symbols]

[0039] 1. Fiber reinforced plastic pipe (FRPM pipe) 2 Core layer 3. Inner fibrous layer 3a, 3c Circumferential fiber layer 3b Axial fiber layer 4 Outer fiber layer 4a Circumferential fiber layer 4b Axial fiber layer 5. One-way woven roving 5a Roving 5b Connecting thread 6 Inner protective layer 7 Outer protective layer 8. Impact Test Equipment 9 Swing Axis 10 Arm 11 Weight 12 protrusions 13 Supporting wall

Claims

1. The inflatable sack has a cylindrical core layer (2) and at least one of an inner fiber layer (3) formed by impregnating fibers with a resin and laminated inside the core layer (2) and an outer fiber layer (4) formed by impregnating fibers with a resin and laminated outside the core layer (2), At least one of the inner fiber layer (3) and the outer fiber layer (4) has an axial fiber layer (3b, 4b) having rovings (5a) arranged at predetermined intervals along the axial direction of the pipe, the intervals between the rovings (5a) of the axial fiber layers (3b, 4b) being in the range of 0.1 mm to 2.5 mm, and the pipe thickness being in the range of 5 mm to 10 mm.

2. 2. A fiber-reinforced resin pipe according to claim 1, comprising the inner fiber layer (3).

3. The weight of the axial fiber layers (3b, 4b) is 250 g / m ２ The fiber-reinforced resin pipe according to claim 2 .

4. 2. The fiber-reinforced resin pipe according to claim 1, wherein the spacing between the rovings (5a) of the axial fiber layers (3b, 4b) is within a range of 0.1 mm to 2.0 mm.

5. The weight of the axial fiber layers (3b, 4b) is 325 g / m ２ The fiber-reinforced resin pipe according to claim 4 .

6. 2. The fiber-reinforced resin pipe according to claim 1, wherein the axial fiber layers (3b, 4b) consist of a single layer.

7. 7. The fiber-reinforced resin pipe according to claim 1, wherein the roving (5a) is a glass roving.

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